Laminar flow bin

ABSTRACT

Laminar flow in a bin for solid particulate material is provided by a multiple opening bin bottom formed by multiple, substantially identical hoppers arranged in side-by-side adjacency and having an upper inlet area in toto substantially occupying the cross-sectional area of the bin. The hoppers preferably have a hexagonal inlet cross section and have an inclined funnel inner surface with a slope of at least 55*. The hoppers are designed to be prefabricated and installed on a supporting framework independently of the bin peripheral wall.

United States Patent 1191 1111 3,863,811 Fisher et al. Feb. 4, 1975 LAMINAR FLOW BIN 1,686,077 10/1928 Evans 222/462 x 2,948,437 8/1960 Nielsen: i 1 222/185 X [75] lnventrs- Glen Bellevue, Fred 3,173,582 3/1965 Walter 222/145 x Franz, Mercer Island, both of Wash.

[73] Assignee: Technovators, Inc., Seattle, Wash. Primary Examiner-Stanley H. Tollberg Filed: y 1973 Attorney, Agent, or Fzrm-Dowrey & Cross [21] Appl. No.: 358,866 [57] ABSTRACT Related U.S. Application Data Laminar flow in a bin for solid particulate material is [63] Continuation Of Set, NO. 145,648, May 21, 1971, i by a mulFlple 9 bomm fOrmed 2 wand/16 multiple, substant1ally 1dent1cal hoppers arranged in side-by-side adjacency and having an upper inlet area [52] U.S. (Il. 222/145 in tow Substantially Occupying the cross-Sectional area [51] Int. Cl B67d 5/60 of the The hoppers Preferably have a hexagonal [58] Fi ld f S h 222/145 1 5 435 43 inlet cross section and have an inclined funnel inner 222/5 5 462 132 47g; 141/331 342 surface with a slope of at least 55. The hoppers are designed to be prefabricated and installed on a sup- [5 R f r it porting framework independently of the bin peripheral UNITED STATES PATENTS wall- 1,420,039 6/1922 Horstkotte 141/338 17 Claims, 8 Drawing Figures PATENTEU E 1%.

sum 1 OF 4 Mac 11,

INVENTORS GLEN W. FISHER FRED A. FRANZ BY gw @w ATTORNEYS PAIEHIEB M SHEEI 2 OF 4 /NVENTORS GLEN W. FISHER FRED A. FRANZ BY M J ww,q/

AT TORNE YS PATENTEDFEB 41915 3, 863 ,811

SHEET 3 OF 4 FIG 3A FIGO 3B i h I 32 five 2 32 INVENTORS GLEN W. FISHER FRED A. FRANZ ATTORNEYS Pmamiurwmms 3.863.811

SHEET H-UF 4 INVENTORS FIG; 5 I GLEN w. FISHER FRED A. FRANZ ATTORNEYS 1 LAMINAR FLOW BIN This is a continuation, of application Ser. No. 145,648 filed /21/71 now abandoned.

This invention relates to the subject matter of US. Pat. No. 3,575,321, and more particularly to solid particulate material bins adopted for use in conjunction with the subject matter of US. Pat. No. 3,575,321 to provide laminar flow bins.

Heretofore, the prior art has attempted to provide mass flow bins, so-called to identify and define the dynamic condition of all particulate material within a bin moving simultaneously. In the broadest sense, a mass flow bin embodies such characteristics that there exist no dead spots therein.

The prior art has, more specifically, provided a mass flow bin design incorporating a single, steep-walled hopper below an elongated bin wherein there not only exist no dead spots but wherein the particulate material within the bin per se flows in a laminar manner. That is to say, adjacent particles within the bin per se move vertically downward at equal velocity, and, hence in laminar flow. Within any hopper, however, laminar flow does not exist inasmuch as those particles directly overhead of the hopper outlet will reach the outlet ahead of those particles (formerly coplanar with the previously-mentioned particles at the commencement of the hopper) adjacent the bin side walls. Because of the steepness of the hopper walls in this prior art design, the differential discharge period of the formerly co-planar particles (called the hopper effect) is relatively small when compared with the period within which the particles traverse the hopperper'se. But because of the practical size limitations of commercial bins combined with the steepness of the hopper walls, the hopper per se occupies a substantial and significant portion of the overall height of the bin structure (bin plus hopper), and, hence, when compared with the total period within which a particle traverses the bin per se the hopper effect is substantial.

Other prior art bin designs have attempted to provide mass flow bins with laminar flow characteristics by incorporating vertical partitions within the bin per se, by incorporating multiple hoppers or multiple opening hoppers, and by combinations of the above. However, these prior art designs have not reliably achieved laminar bin flow inasmuch as their bin flow characteristics, such as the tendency for one or more of the multiple bin outlets to preferentially pass material thereby creating a funneling condition within the bin, are not consistent from one installation to another and are not necessarily consistent within the same installation.

The present invention provides a laminar flow bin having a multiple opening bin bottom. The bin bottom comprises multiple, substantially identical hoppers arranged in side-by-side adjacency and having an upper inlet area in toto substantially occupying the cross sectional area of the bin as defined by the bin peripheral wall, The multiple opening bin bottom is designed for elevated positioning with respect to a base plane such that particulate material discharge means may be located beneath the bin bottom and spouted to the multiple hopper outlets for controllable withdrawal of particulate material from the bin through the hopper outlets. This feature is especially suitable for bin bottomsdesigned for installation in concrete slip-formed bins but alSo is suitable for bin bottoms designed for installation in bins having peripheral walls fabricated by other methods.

The preferred form of the invention includes hopper modules that may be prefabricated and installed on or in a supporting framework. This feature enables the standardization of bin design for laminar flow bins while at the same time permitting variation in bin design to accomodate the various bin diameters and heights needed for customizing a bin to particular user requirements.

Each hopper inlet could be fabricated in a number of geometries as viewed in plan. However, a hexagonal geometry minimizes the hopper effect to a significantly greater degree than any other geometry and also is an optimum geometry from the standpoint of hopper fabrication cost, structural integrity of the bin bottom and assembly of the bin bottom with hopper modules. Therefore, the hexagonal geometry is preferred.

Utilizing hoppers having hexagonal geometries necessitates the provision of other geometries to complete the periphery of a bin bottom designed for rectangular or circular bins. In the case of rectangular bins, the peripheral bin bottom gaps between hexagonal hoppers can be filled with hoppers having an inlet with a one half hexagonal geometry. In the case of circular bins, the peripheral gaps must be filled by hoppers having an inlet of more complicated geometry, such as is illustrated in the appended drawings. In both cases, however, the peripheral filler hoppers can be modularized and prefabricated.

Referring now to the figures:

FIG. 1 is a top plan view of the bin bottom assembly of this invention;

FIG. 2 is a cross section taken along the line 22 of FIG. 1;

FIG. 3 is an enlarged vertical cross section of two hopper modules taken along the line 33 of FIG. 1;

FIGS. 3a, b and c are detail views of the joinder of hopper modules, 3 a and b being in vertical sections, and 3 c in top plan;

FIG. 4 is an enlarged top plan view of two peripheral hopper modules; and

FIG. 5 is a cross section taken along the line 5-5 of FIG. 1 with a schematic illustration of particulate material discharge control means.

With reference to the drawings which illustrate a preferred modularized bin bottom for a circular bin, bin 10 comprises an annular peripheral wall 12 extending upward from base 14. A bin bottom assembly 16 compose d ofmultiple, substantially identical hopper modules 18 with suitable filler hopper modules 20 provided to closely conform the bin bottom hopper inlet area to the cross section area bounded by peripheral wall 12.

The hopper modules shown are fabricated of metal, preferably stainless steel, but alternately of another metal, the material contacting surfaces of which may be coated with a low friction material such as Teflon a fluorocarbon compound formulated by the du Pont Company. Alternately the hopper modules may be fabricated of concrete. As shown (e.g., FIG. 1), the hopper modules 18, providing in toto a hopper inlet area equal to substantially the entire cross sectional area enclosed by peripheral wall 12, each comprise a funnel section 22 having a hopper inlet 24 of hexagonal geometry, a hopper outlet 26 of circular geometry, and a side wall 28 extending therebetween and suitably transposing from the hexagonal geometry to the circular outlet geometry (e.g. FIG. 3). Each hopper module 18 also comprises an exterior vertical section 30 of hexagonal geometry in horizontal section peripherally enclosing and abutting the upper portion of funnel section 22. The upper edge portion 22a of funnel section 22 is vertical and is secured to vertical section 30 by suitably placed plug welds 32 (FIG. 3a). Each hopper outlet 26 is suitably flanged for attachment to appropriate spoutmg.

The funnel sections and enclosing vertical sections of the peripheral filler hopper modules 20 (FIG. 4) are similarly constructed, considering those differences necessitated by the different plan geometry. As shown in FIG. 4, each such funnel section could be divided to provide two or more hopper outlets if desired.

The hopper modules shown are designed for support by a framework 34 (FIGS. 2 and comprising several parallel joists 36 supported by beams 38 in turn supported by pillars 40. The joists are so positioned that each joist extends beneath the hopper vertical sections and intermediate adjacent hopper outlets so that each hopper module 18 is supported by two joists. Certain of the peripheral filler hopper modules are supported by auxilliary joists 42 as shown in FIG. 1. The hopper module vertical sections extend downwardly a sufficient distance to rest on the joists 36, 42 with clearance between the joists and the hopper module funnel sections. Thus, the hopper module funnel sections are suspended by their respective vertical sections.

The hopper modules are assembled in side-by-side adjacency with their respective vertical sections abutting adjacent modules. The abutting vertical section walls are then secured together, as by bolts 44 (FIG. 3), preferably near their lower edges where sufficient working clearance with the funnel sections exists. The upper edge of the abutting vertical sections at each Y juncture (FIG. 3c)'are preferably seam welded and the intervening edge capped with an inverted U-shaped member 45 filled with a resilient seal 47. Alternately the upper edge of each vertical section could be flanged to seat upon the upper edge of the respective vertical section edges 22a as shown in FIG. 3b and welded thereto.

As thus far described, the modular bin bottom assembly 16 is independent of the bin peripheral wall 12. An annular flange 46 (FIG. 2) is secured to the interior of peripheral wall 12 at about the elevation of the joist upper surface to serve as a grout support. The annular space between the bin bottom assembly 16 and the inner surface of peripheral wall 12 is filled with grout 48, the upper surface of which is tapered upwardly and outwardly, to seal that space from particulate material. The grout not only seals the space but serves as a shim for the bin bottom assembly 16 to prevent lateral movement thereof.

To minimize the hopper effect, each hopper module funnel section side wall has a valley of at least about 55 and preferably about 60, an optimum. The valley angle could be greater but without significantly decreasing the hopper effect when compared with such factors as increased fabrication costs due to more material being required to fabricate larger funnel sections and concommitantly larger vertical sections.

Within the space between base 14 and the bin bottom assembly 16, particulate material discharge means 50 (FIG. 5) is provided and connected in fluid communication to the hopper outlets by spouting 52. Means 50 preferably comprises one or more blending devices operable in accordance with the teachings of U.S. Pat. No. 3,575,321 (which teachings are herein incorporated by this reference thereto as though fully set forth herein) to combine multiple streams in pre-selected proportions independent of upstream conditions such that the withdrawal rate from each hopper outlet is controlled by the flow rate of the combined stream or streams. Applied to the present embodiment, five such blending devices are provided with six full-sized hopper outlets spouted to the first two blending devices 54, 56, seven full-sized hopper outlets spouted to the third blending device 58, the peripheral filler hopper outlets spouted to the fourth blending device 60, and the outlets from the aforementioned four blending devices spouted to the fifth blending device 62.

Five such blending devices are employed simply as a matter of practical convenience. One large capacity blending device should be employed or more than five could just as readily be utilized. In all cases, the net effect is that the final flow rate restriction 64, in accordance with the teachings of U.S. Pat. No. 3,575,321, is the controlling flow rate of the entire bin discharge system.

Alternative flow control means suitable for use with the bin bottom assembly, although substantially less desirable than the subject of U.S. Pat. No. 3,575,321, because they are neither as precise nor as predictable, include devices designed to blend streams based on (1) equal angle of repose of the streams during the combining thereof, (2) equal upstream pressures exerted on the streams during the combining thereof, (3) metered orifice control of the streams.

As a result of the above-described flow rate control exercised by means 50 and in conjunction with the proportional relationship between means 50 and the hopper modules, particulate material flow through the bin per se will be laminar to a plane just above the commencement of the inclined hopper module funnel section side walls. In a sixteen foot diameter bin, this critical plane will exist only a few inches above the plane defined by the commencementof the inclined side walls. To insure that there is no particulate material crossflow between this critical plane and the hopper funnel sections, the vertical upper edge portions (e.g., 22a) of the funnel sections are extended upwardly to an elevation above this critical plane.

Furthermore, since in other bin designs a locus of peripheral overpressure on the bin peripheral wall has occurred at the plane where the bin section per se ends and the hopper section commences, the vertical upper edge portions (e.g. 22a) of the funnel sections are provided to intercept any such overpressure condition to prevent the same from accumulating in an additive fashion and being exerted against the peripheral wall 12. Any such overpressure in the present design will be borne by the abutting vertical sections of the hopper modules.

While the preferred form of the invention has been illustrated and described it should be understood that the invention is not to be limited thereby. The principles of the invention are equally applicable to other embodiments well within the skill of the art. Accordingly the invention is to be limited only by a literal interpretation of the claims appended hereto.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. A laminar flow bin for solid particulate material which comprises a peripheral wall; a multiple opening bottom comprising multiple, substantially identical, open-topped hoppers arranged in side-by-side adjacency, each hopper having an upper hexagon inlet and a smaller lower outlet in axial alignment with the upper inlet and an inner surface inclining downward from the upper inlet to the lower outlet at a slope of at least 55, the hopper inlets occupying in toto substantially the entire cross sectional area enclosed by said peripheral wall, each said hexagonal inlet being contiguous with at least three additional hexagonal inlets; and particulate material discharge means spouted to each hopper outlet to controllably permit particulate material to discharge from each hopper outlet at substantially the same rate.

2. The bin of claim 1 wherein each said hopper is a prefabricated module comprised of a funnel section providing the upper inlet, lower outlet and inclined inner surface, and a peripheral section enclosing and secured to the funnel section for support of the funnel section and for attachment to adjacent hopper module peripheral sections.

3. The bin of claim 2 wherein said funnel section is provided with a vertical upwardly extending edge of the same peripheral geometry as said upper inlet, and wherein said peripheral section comprises a skirt member enclosing and secured to said edge and extending vertically downward to an elevation suitable for loadbearing contact with a bin bottom support.

4. A modular bin bottom assembly for a mass flow bin which comprises multiple, substantially identical, open-topped hoppers arranged in side-by-side adjacency, each hopper being a discrete unit having an upper hexagonal inlet and a smaller lower outlet in axial alignment with the upper inlet and an inner surface inclining downward from the upper inlet to the lower outlet at a slope sufficiently steep thatmass flow occurs in said-hopper, the hopper inlets occupying in toto substantially the entire cross sectional area of the bin, each said hexagonal inlet being contiguous with at least three additional hexagonal inlets.

5. The bin bottom assembly of claim 4 wherein each said hopper is a prefabricated module comprised of a funnel section providing the upper inlet, lower outlet and inclined inner surface, and a peripheral section enclosing and secured to the funnel section for support of the funnel section and for'attachment to adjacent hopper module peripheral sections.

6. The bin bottom assembly of claim 5 wherein said funnel section is provided with a vertical upwardly extending edge of the same peripheral geometryas said upper inlet, and wherein said peripheral section comrpises a skirt member enclosing and secured to said edge and extending vertically downward to an elevation suitable for load-bearing contact with a bin bottom support.

7. A laminar flow bin for solid particulate material which comprises:

A. a vertical peripheral wall defining a storage volume consisting of substantially all of the particulate material storage space within the bin; and

B. hopper discharge means at the lower end of the storage volume for effecting discharge of particulate material from the storage volume under laminar flow conditions throughout substantially the entire length of the storage volume, said hopper discharge means including:

1. a plurality of substantially identical, opentopped hoppers arranged in side-by-side adjacency, each said hopper including an upper inlet, a lower outlet smaller than and in axial alignment with said upper inlet on the same vertical axis, and an inner surface inclining downwardly from said upper inlet to said lower outlet at a slope of at least 55, said upper inlets occupying the entire central cross sectional area and occupying in toto substantially the entire cross-sectional area enclosed by said vertical peripheral wall; and

2. flow control means regulating particulate material discharge from said hoppers for effecting particulate material discharge simultaneously from each hopper at a rateproportional to the relative cross-sectional area of each such hopper.

8. The bin of claim 7 wherein each said hopper inlet has a hexagonal geometry in plan view.

9. The bin of claim 8 wherein each said hopper is a prefabricated module comprised of a funnel section providing the upper inlet, lower outlet and inclined inner surface, and a peripheral section enclosing and secured to the funnel section for support of the funnel section and for attachment to adjacent hopper module peripheral sections.

10. The bin of claim 9 wherein said funnel section is provided with a vertical upwardly extending edge of the same peripheral geometry as said upper inlet, and wherein said peripheral section comprises a skirt member enclosing and secured to said edge and extending vertically'downward to an elevation suitable for loadbearing contact with abin bottom support.

11. The bin of claim 10 including open-topped filler hoppers, each having an upper inlet and a smaller outlet and an inner surface inclining downward from the upper inlet tothe lower outlet at a slope of at least 55, said filler hoppers being of suitable geometry at the filler hopper inlets and located around the periphery of said hoppers to substantially match the overall bin bottom area to the cross-sectional area enclosed by said peripheral wall, said particulate material discharge means being spouted to each filler hopper outlet to controllably permit particulate material to discharge from each filler hopper outlet at a rate proportional to the relative cross-sectional area of each such filler hopper.

12. The bin of claim 1 including open-topped filler hoppers, each having an upper inlet, a smaller outlet and an inner surface inclining downward from the upper inlet to the loweroutlet at a slope of at least 55, said filler hoppers being of suitable geometry at the filler hopper inlets and located around the periphery of said first-mentioned hoppers to substantially match the overall bin bottom area to the cross-sectional area enclosed by said peripheral wall; said particulate material discharge means being spouted to each filler hopper- A. a vertical peripheral wall defining a storage 'volume consisting of substantially all of the particulate material storage space within the bin; and

B. hopper discharge means at the lower end of the 1 storage volume for effecting discharge of particulate material from the storage volume under laminar flow conditions throughout substantially the entire length of the storage volume, said hopper discharge means including:

1. a plurality of open-topped hoppers arranged in side-by-side adjacency, each said hopper including an upper inlet, a lower outlet smaller than said upper inlet, and an inner surface inclining downward from the upper inlet to the lower outlet at a slope sufficiently steep that mass flow occurs in said hopper, the hopper inlets occupying the entire cross sectional area and occupying in toto substantially the entire cross-sectional area enclosed by said vertical peripheral wall;

2. hopper module support means below and in load-bearing contact with said hoppers for vertically supporting said hoppers independently of said vertical peripheral wall; and

3. flow control means regulating particulate material discharge from said hoppers for effecting particulate material discharge simultaneously from each hopper at a rate proportional to the relative cross-sectional area of each such hopper.

hoppers, each having an upper inlet and a. smaller out- 14. The bin of claim 13 wherein each said hopper inlet has a hexagonal geometry inplan view.

15. The bin of claim 13 wherein each said hopper is a prefabricated module'comprised of a funnel section providing the upper inlet, lower outlet and inclined inner surface, and a peripheral section enclosing and secured to the funnel section for support of the funnel section and for attachment to adjacent hopper module peripheral sections.

16. The bin of claim 15 wherein said funnel section is provided with a vertical, upwardly extending edge of the same peripheral geometry as said upper inlet, and wherein said peripheral section comprises a skirt member enclosing and secured to said edge and extending vertically downward to an elevation suitable for loadbearing contact with a bin bottom support.

17. The bin of claim 13 including open-topped filler let and an inner surface inclining downward from the upper inlet to the lower outlet at a slope sufficiently steep that mass flow occurs in said filler hopper, said filler hoppers being of suitable geometry at the tiller hopper inlets and located around the periphery of said first-mentioned hoppers to substantially match the overall bin bottom area to the cross-sectional area enclosed by said peripheral wall. 

1. A laminar flow bin for solid particulate material which comprises a peripheral wall; a multiple opening bottom comprising multiple, substantially identical, open-topped hoppers arranged in side-by-side adjacency, each hopper having an upper hexagon inlet and a smaller lower outlet in axial alignment with the upper inlet and an inner surface inclining downward from the upper inlet to the lower outlet at a slope of at least 55*, the hopper inlets occupying in toto substantially the entire cross sectional area enclosed by said peripheral wall, each said hexagonal inlet being contiguous with at least three additional hexagonal inlets; and particulate material discharge means spouted to each hopper outlet to controllably permit particulate material to discharge from each hopper outlet at substantially the same rate.
 1. a plurality of open-topped hoppers arranged in side-by-side adjacency, each said hopper including an upper inlet, a lower outlet smaller than said upper inlet, and an inner surface inclining downward from the upper inlet to the lower outlet at a slope sufficiently steep that mass flow occurs in said hopper, the hopper inlets occupying the entire cross sectional area and occupying in toto substantially the entire cross-sectional area enclosed by said vertical peripheral wall;
 1. a plurality of substantially identical, open-topped hoppers arranged in side-by-side adjacency, each said hopper including an upper inlet, a lower outlet smaller than and in axial alignment with said upper inlet on the same vertical axis, and an inner surface inclining downwardly from said upper inlet to said lower outlet at a slope of at least 55*, said upper inlets occupying the entire central cross sectional area and occupying in toto substantially the entire cross-sectional area enclosed by said vertical peripheral wall; and
 2. flow control means regulating particulate material discharge from said hoppers for effecting particulate material discharge simultaneously from each hopper at a rate proportional to the relative cross-sectional area of each such hopper.
 2. hopper module support means below and in load-bearing contact with said hoppers for vertically supporting said hoppers independently of said vertical peripheral wall; and
 2. The bin of claim 1 wherein each said hopper iS a prefabricated module comprised of a funnel section providing the upper inlet, lower outlet and inclined inner surface, and a peripheral section enclosing and secured to the funnel section for support of the funnel section and for attachment to adjacent hopper module peripheral sections.
 3. The bin of claim 2 wherein said funnel section is provided with a vertical upwardly extending edge of the same peripheral geometry as said upper inlet, and wherein said peripheral section comprises a skirt member enclosing and secured to said edge and extending vertically downward to an elevation suitable for load-bearing contact with a bin bottom support.
 3. flow control means regulating particulate material discharge from said hoppers for effecting particulate material discharge simultaneously from each hopper at a rate proportional to the relative cross-sectional area of each such hopper.
 4. A modular bin bottom assembly for a mass flow bin which comprises multiple, substantially identical, open-topped hoppers arranged in side-by-side adjacency, each hopper being a discrete unit having an upper hexagonal inlet and a smaller lower outlet in axial alignment with the upper inlet and an inner surface inclining downward from the upper inlet to the lower outlet at a slope sufficiently steep that mass flow occurs in said hopper, the hopper inlets occupying in toto substantially the entire cross sectional area of the bin, each said hexagonal inlet being contiguous with at least three additional hexagonal inlets.
 5. The bin bottom assembly of claim 4 wherein each said hopper is a prefabricated module comprised of a funnel section providing the upper inlet, lower outlet and inclined inner surface, and a peripheral section enclosing and secured to the funnel section for support of the funnel section and for attachment to adjacent hopper module peripheral sections.
 6. The bin bottom assembly of claim 5 wherein said funnel section is provided with a vertical upwardly extending edge of the same peripheral geometry as said upper inlet, and wherein said peripheral section comrpises a skirt member enclosing and secured to said edge and extending vertically downward to an elevation suitable for load-bearing contact with a bin bottom support.
 7. A laminar flow bin for solid particulate material which comprises: A. a vertical peripheral wall defining a storage volume consisting of substantially all of the particulate material storage space within the bin; and B. hopper discharge means at the lower end of the storage volume for effecting discharge of particulate material from the storage volume under laminar flow conditions throughout substantially the entire length of the storage volume, said hopper discharge means including:
 1. a plurality of substantially identical, open-topped hoppers arranged in side-by-side adjacency, each said hopper including an upper inlet, a lower outlet smaller than and in axial alignment with said upper inlet on the same vertical axis, and an inner surface inclining downwardly from said upper inlet to said lower outlet at a slope of at least 55*, said upper inlets occupying the entire central cross sectional area and occupying in toto substantially the entire cross-sectional area enclosed by said vertical peripheral wall; and
 2. flow control means regulating particulate material discharge from said hoppers for effecting particulate material discharge simultaneously from each hopper at a rate proportional to the relative cross-sectional area of each such hopper.
 8. The bin of claim 7 wherein each said hopper inlet has a hexagonal geometry in plan view.
 9. The bin of claim 8 wherein each said hopper is a prefabricated module comprised of a funnel section providing the upper inlet, lower outlet and inclined inner surface, and a peripheral section enclosing and secured to the funnel section for support of the funnel section and for attachment to adjacent hopper module peripheral sections.
 10. The bin of claim 9 wherein said funnel section is provided with a vertical upwardly extending edge of the same peripheral geometry as said upper inlet, and wherein said peripheral section comprises a skirt member enclosing and secured to said edge and extending vertically downward to an elevation suitable for load-bearing contact with a bin bottom support.
 11. The bin of claim 10 including open-topped filler hoppers, each having an upper inlet and a smaller outlet and an inner surface inclining downward from the upper inlet to the lower outlet at a slope of at least 55*, said filler hoppers being of suitable geometry at the filler hopper inlets and located around the periphery of said hoppers to substantially match the overall bin bottom area to the cross-sectional area enclosed by said peripheral wall, said particulate material discharge means being spouted to each filler hopper outlet to controllably permit particulate material to discharge from each filler hopper outlet at a rate proportional to the relative cross-sectional area of each such filler hopper.
 12. The bin of claim 1 including open-topped filler hoppers, each having an upper inlet, a smaller outlet and an inner surface inclining downward from the upper inlet to the lower outlet at a slope of at least 55*, said filler hoppers being of suitable geometry at the filler hopper inlets and located around the periphery of said first-mentioned hoppers to substantially match the overall bin bottom area to the cross-sectional area enclosed by said peripheral wall; said particulate material discharge means being spouted to each filler hopper outlet to controllably permit particulate material to discharge from each filler hopper outlet at a rate proportional to the relative cross-sectional area of each such filler hopper.
 13. A laminar flow bin for solid particulate material which comprises: A. a vertical peripheral wall defining a storage volume consisting of substantially all of the particulate material storage space within the bin; and B. hopper discharge means at the lower end of the storage volume for effecting discharge of particulate material from the storage volume under laminar flow conditions throughout substantially the entire length of the storage volume, said hopper discharge means including:
 14. The bin of claim 13 wherein each said hopper inlet has a hexagonal geometry in plan view.
 15. The bin of claim 13 wherein each said hopper is a prefabricated module comprised of a funnel section providing the upper inlet, lower outlet and inclined inner surface, and a peripheral section enclosing and secured to the funnel section for support of the funnel section and for attachment to adjacent hopper module peripheral sections.
 16. The bin of claim 15 wherein said funnel section is provided with a vertical, upwardly extending edge of the same peripheral geometry as said upper inlet, and wherein said peripheral section comprises a skirt member enclosing and secured to said edge and extending vertically downward to an elevation suitable for load-bearing contact with a bin bottom support.
 17. The bin of claim 13 including open-topped filler hoppers, each having an upper inlet and a smaller outlet and an inner surface inclining downward from the upper inlet to the lower outlet at a slope sufficiently steEp that mass flow occurs in said filler hopper, said filler hoppers being of suitable geometry at the filler hopper inlets and located around the periphery of said first-mentioned hoppers to substantially match the overall bin bottom area to the cross-sectional area enclosed by said peripheral wall. 